To remove the inserts you do need to remove the struts completely:
Slacken off the main shock insert nut (normally 18mm deep socket) under the little plastic cover on the strut mount top while the car is on the floor
Jack car up with rear wheel chocked.
Remove wheels.
Undo 13mm bolts securing ARB links.
Undo the two 17mm bolts securing the caliper, remove caliper out of the way and support so not pulling on the pipe.
Undo 17mm nut on steering rack end and seperate joint using a splitter (nut type work best).
Undo 19mm nut securing strut to wishbone and seperate joint with a splitter.
Disconnect the cables for ABS and brake pad wear sensor from strut leg
If ABS is fitted remove the sensor from the back of the hub - 5mm allen key
Disconnect the cables for ABS and brake pad wear sensor from strut leg.
Supporting the leg from below undo the 3 13mm nuts securing the top mount to the strut tower.
The strut will now be free to remove
Compress the springs using a proper spring compressor (about £15 from GSF)
Remove the shock insert nut followed by the top strut mount and top hat.
You can now remove the spring - uncompress it
Undo the strut locking collar/ringnut. Various styles out there but if the oem you will see 4 holes in the top, using a hammer and metal bar tap it to undo. You may need to soak it with WD40 or similiar.
The strut will now slide out, be careful as there is oil in the bottom of the strut - it's meant to be there.
Refitting is the reverse of all the above
I did the above a couple of weeks back to find my collar nuts don't fit and will have to go through it all again when the replacement parts turn up
HTH
Charlie
